Research ArticleMechanical Properties of Scrap Tire Crumbs-Clayey Soil MixturesDetermined by Laboratory Tests

ShanShan Li1 and Dayong Li 1,2

1College of Civil Engineering and Architecture, Shandong University of Science and Technology, Qingdao 266590, China2College of Civil Engineering, Fuzhou University, Fuzhou 350116, China

Correspondence should be addressed to Dayong Li; ldydy@163.com

Received 15 August 2017; Revised 6 November 2017; Accepted 26 November 2017; Published 15 February 2018

Academic Editor: Jun Liu

Copyright © 2018 ShanShan Li and Dayong Li. *is is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Some laboratory tests, such as Proctor compaction test, direct shear and cyclic direct shear tests, consolidation test, and un-confined compression test, were performed on scrap tire crumbs-clayey soil mixtures to study the mechanical properties of themixtures. *e results show that (1) the maximum dry unit weight and the corresponding optimum moisture content of themixtures decrease rapidly with the increase of scrap tire crumbs content (CSTC), showing good potential for using the mixtures aslightweight fill material; (2) it is not possible to prepare the mixture when CSTC exceeds 30% due to the occurrence of cracks in themixture after removing from a mould; and (3) the shear strength of mixtures approximately increases by 20% when CSTC is up to30%, while the residual strength decreases by 15%, compared with that of pure clayey soil. During shearing, the dilation of themixtures occurs, particularly under the condition of a high CSTC and a low vertical pressure. Besides, the compressive strength andconsolidation settlement of the mixtures decrease with CSTC increasing.*e results indicate that it is possible for scrap tire crumbsused to improve clayey soil, which is suitable to act as a fill material.

1. Introduction

Six hundred million scrap tires were generated in China by2015, while two hundred million scrap tires still remained instockpiles [1]. Huge quantities of scrap tires were generatedin other countries as well. For example, nearly three hundredmillion scrap tires were generated in the European Union by2015 [2]; two hundred million scrap tires were generated inthe US [3]; and one hundred and fifty million scrap tireswere estimated to be generated per year in India [4]. Landfilling or stockpiling of scrap tires is prone to cause envi-ronmental problems, such as (a) largely occupied spaces, (b)health hazards (scrap tires will provide a natural breedingplace for diseases caused by insects and rodents), and (c) airpollution (stockpiling of scrap tires could pose a major firerisk and then cause air pollution). *erefore, there exists anurgent need to explore new and beneficial ways to recycle orreuse scrap tires.

Scrap tire pieces have been applied in civil engineering,such as using as embankment fill material [5–8], drainage

material to collect leachate landfill [9], retaining wall backfillmaterial [10, 11], and bridge abutment fill material [12].Laboratory testing and field demonstration of the applicationof sands mixed with scrap tire pieces with various shapes andsizes have shown that the ductility and shear strength of sandscould be significantly enhanced [13]. Furthermore, themixture has lower unit weight and higher compressibility,compared with clean sands [14].

It is concluded that scrap tire pieces with various shapesand sizes can be successfully used for modification of sand.However, it is necessary to study effects of amounts of scraptire pieces on the mechanical performance for clayey soil.Hasan et al. [15] and Sellaf et al. [16] investigated the me-chanical properties of scrap tire chips-cohesive clayey soilmixtures. *e results revealed that it is possible to use clayeysoil mixed with tire chips as a fill material. Attom et al. [17]found that increasing the content of scrap tire shreds canimprove the shear strength and permeability of clayey soil butcan cause a decrease in the plasticity index, the expansionpressure, and expansion potential, compared with that of pure

HindawiAdvances in Materials Science and EngineeringVolume 2018, Article ID 1742676, 10 pageshttps://doi.org/10.1155/2018/1742676

clayey soil. Kalkan [18] concluded that the silica fume-scraptire rubber �ber mixture materials can be used to improveclayey soils.

�e mechanical properties of scrap tire crumbs-clayeysoil mixtures, such as shear strength, residual shear strength,uncon�ned compressive strength, and consolidation set-tlement, were explored by a series of laboratory tests. �reescrap tire crumbs contents (CSTC), 10, 20 and 30%, were usedin this study. �e e�ects of the CSTC on the mechanicalproperties of the mixtures were discussed.

2. Materials

2.1. Soil Specimens. Figure 1 shows the materials used in theexperiments. �e components of clayey soil are shown inTable 1. Besides, the engineering parameters of clayey soilwere measured according to the Standard for Soil TestMethod (GB/T50123) [19]. Such parameters are summarizedin Table 2.

2.2. Scrap Tire Crumbs. Scrap tire crumbs were obtainedfrom a local rubber processing factory. It should be notedthat the steel and �u� in the scrap tire crumbs have beenremoved. �e scrap tire crumbs vary from 0.5 to 4.5mm indiameter. �e speci�c gravity of scrap tire crumbs was tested

to 1.15 according to ASTM C127 (2007) [20]. �e sieveanalysis of scrap tire crumbs was determined according toASTMD422-63 (1998) [21]. �e result of the sieve analysis isshown in Figure 2.

3. Experiment Descriptions

3.1. Sample Preparation. Hasan et al. [15] found that theshear strengths increase up to 30% for �ne tire chip and 20%for coarse tire chip-cohesive clayey soil mixtures. �e di-ameter of �ne tire chips is less 0.425mm, and the diameter ofcoarse tire chips is between 2 and 4.75mm. Moreover, it isnot possible to prepare the mixture when CSTC exceeds 30%due to the occurrence of cracks in the mixture after re-moving from a mould. �erefore, the content of scrap tirecrumbs used in this study is less than 30%. �e scrap tirecrumbs content, CSTC, is de�ned as the ratio of weight ofscrap tire crumbs to the total dry weight of the mixture [15].

�e process of preparing the mixtures includes threesteps:

Step 1: the clayey soil was oven-dried at approximately65°C [19], and then the soil mass was ground to par-ticles of less than 0.05mm in diameter.Step 2: the mixtures were compacted at the optimummoisture content to obtain the maximum dry unit

(a) (b)

Figure 1: Test materials. (a) Clayey soil. (b) Scrap tire crumbs.

Table 1: Components of clayey soil.Sand content (%) 3.80Silt content (%) 20.6Clay content (%) 75.6Soil classi�cation Silty clay

Table 2: Some properties of clayey soil.Liquid limit (%) 37.2Plastic limit (%) 17.1Plastic index (%) 20.1Nature void ratio 1.13Speci�c gravity 2.72Nature moisture content (%) 45.5

0.1 1 100

10203040506070

8090

100

Perc

ent p

assi

ng (%

)

Grain size (mm)

Figure 2: Particle-size distribution of scrap tire crumbs.

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weight. For the mixtures with various CSTC, weights ofneeded clayey soil, scrap tire crumbs, and water werecalculated, respectively.�e dry clayey soil particles anddry scrap tire crumbs were mixed uniformly in a lab-oratory mixer. Water needed was then added in thelaboratory mixer until the optimum water content ofthe mixture is reached.Step 3: the mixture was compacted in three equal-thickness layers with a hammer that delivers 25blows to each layer. �e hammer has a mass of 2.5 kgand has a drop of 30.5mm. �e mixture specimenswere obtained using a standard ring sampler, and thespecimens were saturated in a vacuum pump.

To determine the maximum dry unit weight and thecorresponding optimum moisture of the mixtures, theProctor compaction tests were carried out according toASTMD698-78 (1989) [22]. �e variations of maximum dryunit weight and the corresponding optimal moisture contentfor the mixtures are given in Figure 3. It is shown that themaximum dry unit weight and the corresponding optimummoisture of mixtures are less than that of pure clayey soil anddecrease rapidly with CSTC increasing. It is similar to that

found by Kalkan [18] and Akbulut et al. [23], who mixedclayey soil with scrap tire rubber �ber. �e reason of thereduction in maximum dry unit weight of the mixtures is thelow density of scrap tire crumbs [24]. In addition, bibulousrate of the scrap tire crumbs is very low compared with thatof the clayey soil, resulting in the decrease of optimummoisture content for the mixtures.

3.2. Test Methods

3.2.1. Direct Shear Tests. Figure 4 shows the direct/residualshear test apparatus (ShearTrac II) used in this study. �isapparatus is capable of performing the consolidation andshearing phases of a standard direct shear test and cyclic

1.40

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axim

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nit w

eigh

t (g/

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1.78

Dry unit weightOptimal moisture

Figure 3: Variations of dry unit weight and the correspondingoptimal moisture content for mixtures.

Figure 4: Direct/residual shear test apparatus (ShearTrac II).

0 2 4 6 8 10 12 14 16 18 20 220

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200300 kPa

200 kPa100 kPa

Shea

r stre

ss (k

Pa)

Shear strain (%)

50 kPa

CSTC = 20% Clayey soil

Figure 5: Variations of shear stress versus shear strain for mixtures.

50 100 150 200 250 300 35040

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220Sh

ear s

tres

s (kP

a)

Vertical pressure (kPa)

Clayey soilCSTC = 10% CSTC = 20%

CSTC = 30% Fitted curves for mixtures

Figure 6: Mohr–Coulomb failure envelopes for mixtures.

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direct shear tests. Besides, it is capable of performing theconsolidation tests under di�erent stress paths. �e speci-mens were 63.5mm in diameter and 20mm in height.

�e direct shear tests were carried out according to theprocedure described by ASTM D3080-98 (2003) [25]. �evertical pressures of 50, 100, 200, and 300 kPa were applied.During shearing, the shear rates were kept 0.1 and0.8mm/min. �e shear strengths, shear parameters (co-hesion and the angle of internal friction), and volumechanges of the mixtures were derived from test results.

3.2.2. Cyclic Direct Shear Tests. �e cyclic direct shear testswere carried out to elucidate the in�uence of CSTC on theresidual shear strength of mixtures with the apparatusshown in Figure 4. �e mixtures were placed in the shearbox; after about 12 hours (to allow for consolidation),shearing was recommenced at a rate of 0.1mm/min underthe vertical pressure of 50, 100, 200, and 300 kPa,respectively.

3.2.3. Consolidation Tests. One-dimensional consolidationtests for the mixtures using incremental loading wereconducted with the apparatus shown in Figure 4. �emixtures were consolidated at 50, 100, 200, and 300 kPa,respectively, and each vertical pressure increment ismaintained until excessive pore water pressure completelydissipates.

3.2.4. Uncon�ned Compression Tests. �e mixture speci-mens are 39.1mm in diameter and are trimmed to 80mmheight. Compressive strengths of the mixtures with the CSTCof 10%, 20%, and 30% were obtained using a strain rate ofapproximately 3%/min under uncon�ned compactionconditions.

4. Results and Discussion

4.1. Direct Shear Behavior of the Mixture

4.1.1. E�ects of Vertical Pressure and CSTC on ShearStrength. Figures 5–7 compare the results of direct sheartests of pure clayey soil with those of the mixtures. Figure 5shows some typical curves of the shear stress versus shearstrain for the test specimens, where the shear stress hasa general tendency to increase with the shear strain in-creasing. It is similar to the researches by Hasan et al. [15]and Tang et al. [26]. In addition, it should be noted that theshear strength of the mixture is equal to the shear stressat the shear strain of 10% [15].

0 4 8 12 16 20 24 28 3212

16

20

24

28

32

36

40Sh

ear s

treng

th p

aram

eter

CSTC (%)

Angles of internal friction (°)Cohesions (kPa)

Figure 7: Variations of cohesion and internal friction angle formixtures.

0 2 4 6 8 10 120

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180

Shear strain (%)

Shea

r str

ess (

kPa)

Clayey soilCSTC = 10%

CSTC = 20% CSTC = 30%

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Shea

r str

ess (

kPa)

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60

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210

Shear strain (%)

Clayey soilCSTC = 10%

CSTC = 20% CSTC = 30%

(b)

Figure 8: Shear stress-shear strain curves for mixtures undervertical pressure of 200 kPa. (a) Shear rate of 0.8mm/min. (b) Shearrate of 0.1mm/min.

4 Advances in Materials Science and Engineering

�e Mohr–Coulomb failure envelopes and curves of thecohesion and angle of internal friction versus CSTC areshown in Figures 6 and 7. In Figure 6, each point representsthe shear strength of mixtures under a certain verticalpressure, where the shear strengths of mixtures increase withthe increase of vertical pressure. Besides, an approximatelylinear correlation between the shear strength and verticalstress was found in Figure 6. It is also found that CSTC hasa strong in�uence on the shear strength of the mixture. �eshear strength approximately enhances by 20% when CSTC isup to 30%. However, when CSTC is less than 10%, the shearstrength of mixtures decreases compared with that of pureclayey soil.

�e shear strength parameters of mixtures, such as thecohesion and the angles of internal friction, were determinedto further analyze of the e�ect of CSTC on the shear strengthof mixtures. �e cohesion is calculated to be 29.15, 28.11,34.61, and 36.74 kPa for pure clayey soil and themixture withCSTC of 10, 20, and 30%, respectively. Moreover, the angle ofinternal friction is calculated to be 24.46°, 23.38°, 24.18°, and25.83° for pure clayey soil and the mixture with CSTC of 10%,20%, and 30%, respectively. �e relationship between shear

strength parameters and CSTC is illustrated in Figure 7,showing that CSTC has a signi�cant in�uence on the co-hesion of the mixture. However, the angle of internal frictionof mixtures does not change signi�cantly with CSTC in-creasing. With the increase of CSTC, there is an increase inthe friction between clayey soil particles and scrap tirecrumbs, as well as the friction between scrap tire crumbs andscrap tire crumbs. However, the value of CSTC is small(≤30%) in this study. Furthermore, the dilation of mixturesduring shearing will weaken the friction.�erefore, the angleof internal friction does not change signi�cantly with theincrease of CSTC.

4.1.2. E�ects of Shear Rate on Shear Strength. Figure 8 showsthe variations of shear stress with the increase of shear strain

Table 3: E�ects of shear rates on shear strength of mixtures.

CSTC (%) Shear rate (mm/min)Vertical pressure (kPa)50 100 200 300

0 0.1 56.6 83.5 157 2150.8 54.1 71.8 123 160

10 0.1 52.0 81.8 147 2070.8 44.0 71.6 115 156

20 0.1 65.0 92.5 166 2190.8 60.7 75.3 128 168

30 0.1 68.2 99.3 174 229

0 50 100 150 200 250 300 3500

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Shea

r stre

ngth

(kPa

)

Vertical pressure (kPa)

Clayey soilCSTC = 10%, 20%, 30%

Clayey soilCSTC = 10%, 20%, 30%

Shear rate: 0.1 mm/min Shear rate: 0.8 mm/min

Figure 9: �e shear strength of mixtures under di�erent shearrates.

0 1 2 3 4 5 6 7 8 9 10 11 12−0.30

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Clayey soilCSTC = 10%

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0 1 2 3 4 5 6 7 8 9 10 11 12Shear strain (%)

Clayey soilCSTC = 10%

CSTC = 20%CSTC = 30%

−0.35−0.30−0.25−0.20−0.15−0.10−0.05

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sion

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ge in

hei

ght o

f spe

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en (m

m)

(b)

Figure 10: Variations of height of mixtures against shear dis-placement. (a) Under vertical pressure of 50 kPa. (b) Under verticalpressure of 300 kPa.

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for mixtures under vertical pressure of 200 kPa. It indicatesthat there is no peak shear stress observed in the shear stress-shear strain curves. *erefore, the shear stress at the shearstrain of 10% can be used as the shear strength of themixtures. *e shear strengths of mixtures with various CSTCare given in Table 3, and the Mohr–Coulomb failure en-velops for mixtures are shown in Figure 9. *e results showthat when the vertical pressure is less than 100 kPa, the shearstrength of mixtures does not vary significantly with thedecrease of shear rate. However, when the vertical pressureexceeds 100 kPa, the shear strength significantly increaseswith the shear rate increasing.

4.1.3. Effects of Vertical Pressure and CSTC on Volumes ofMixtures. Figure 10 shows the volume changes of themixtures(in height) versus shear strain for the mixtures and possiblespecimen volume compression (with a “−” sign) and dilation(with a “+” sign) shown in this figure. It was found that, whenthe vertical pressure is 50 kPa, the clayey soil and the mixture

with CSTC of 10% compress during shearing. However, themixture with CSTC of 20% initially compresses and thenbegins to dilate after the shear strain exceeds 4.5%. Fur-thermore, with CSTC of 30%, the mixture compressed atfirst and then began to dilate after the shear strain of 5% to6%. *is shearing dilation for scrap tire rubber shreds-soilmixture was also observed by Hasan et al. [15]. However,when the vertical pressure is 300 kPa, during shearing theclayey soil and the mixtures with CSTC of 10 and 20% arecompressed. It can be concluded that during shearing, thedilation of mixtures occurs, particularly under the condition ofa high CSTC and a low vertical pressure.

4.2. Evaluation of Cyclic Direct Shear Tests Results. *e re-sidual shear strengths of mixtures were obtained from cyclicdirect shear tests. In addition, the volume changes ofmixtures were measured during cyclic direct shearing. *etest results for 48 specimens are presented in Figures 11–13and Table 4. Figure 11 presents the variations of shear stress

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Figure 11: Variations of shear stress versus shear strain for mixtures under vertical pressure of 200 kPa. (a) Clayey soil. (b) CSTC � 10%. (c)CSTC � 20%. (d) CSTC � 30%.

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versus shear strain for mixtures under vertical pressure of200 kPa.

Figure 12(a) presents that the shear stress of mixturesincreases initially, after reaching a maximum value, it de-creases with the shear displacement increasing, indicatinga strain-softening phenomenon for the mixtures. It also canbe found that the peak strength of mixtures enhances withthe increase of CSTC. Conversely, the residual shear strengthsof mixtures rapidly decrease with CSTC increasing. �e re-sidual shear strength of the mixture with CSTC of 30% de-creases by about 15%, compared with that of pure clayey soil.�e reason is that the volume of void in the mixture is largerthan that of the pure clayey soil.

Figure 12(b) shows that, during cyclic direct shearing,the vertical displacements decrease initially and then in-crease with increasing the shear displacement. It can be alsoobserved that the mixtures can e�ectively limit the verticaldeformation under the same shear rate and the same verticalpressure, compared with that of pure clayey soil.

�e envelopes of the residual shear strength for themixtures are shown in Figure 13. �e results reveal that the

residual shear strengths of mixtures gradually decrease withCSTC increasing. However, when the CSTC is larger than 20%,the e�ect of the CSTC on the residual strength of the mixturecan be neglected.

It can be also concluded from Table 4 that the requiredshear displacement to obtain the residual shear strength ofmixture increases with increasing the CSTC value. As theCSTC increases from 10 to 30%, the corresponding maxi-mum shear displacements increase by 45.8%, 79.2%, and102%, respectively, compared with that of pure clayey soil.Furthermore, changes in the moisture contents of themixtures were measured (Table 4). It is concluded that themoisture content increases by an average of 1.3%, com-pared with the initial moisture content of the shear surface.�e increase of moisture content is caused by the increaseof the void ratio of mixture located in shear zone duringcyclic shearing.

4.3. EvaluationofConsolidationTestsResults. �e estimationof consolidation settlement is one of the most important

Table 4: �e results of repeated direct shear tests for mixtures.

Rubber content(%)

Normal stress(kPa)

Peak strength(kPa)

Residual strength(kPa)

Shear displacement at residualstrength (mm)

Moisture content increaseratio (%)

Clayey soil100 83.5 78.5

45∼48 1.58200 157 135300 221 202

10100 71.6 68.7

65∼70 1.15200 140 125300 215 180

20100 88.5 63.5

83∼86 1.46200 137 116300 219 175

30100 95.3 62.6

94∼97 1.27200 155 109300 210 170

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Shea

r stre

ss (k

Pa)

Shear displacement (mm)

Clayey soil

CSTC = 10%

CSTC = 20%

CSTC = 30%

(a)

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men

t (m

m)

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Clayey soil

CSTC = 10%

CSTC = 20%

CSTC = 30%

(b)

Figure 12: Plots of shear stress and vertical deformation of mixtures against shear displacement for mixtures under vertical pressure of200 kPa. (a) Shear stress versus shear displacement. (b) Vertical displacement versus shear displacement.

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procedures in the design of soft ground improvementprojects [17]. Figure 14 shows the changes of consolidationsettlement for pure clayey soil and the mixtures undervarious vertical pressures. When the vertical pressure is lessthan 100 kPa, the consolidation settlement of mixtures doesnot vary signi�cantly with CSTC increasing. However, as thevertical pressure is greater than 100 kPa, the settlements ofthe mixtures with CSTC of 10, 20, and 30% decreased ap-proximately 25%, 12%, and 8%, respectively, compared withthat of pure clayey soil. �e reason of the reduction inconsolidation settlement for mixtures is that, with the in-crease of CSTC, the mixtures tend to be more elastic andresilience.

4.4. Compressive Properties

4.4.1. E�ect of CSTC on Compressive Strength of Mixtures.For each compression test under the undisturbed, remolded,and compacted conditions using a strain-controlled axialload, the compressive strength of mixtures, which is taken asthe load per unit area at 15% axial strain, can be obtained.�e variations of axial stress for the mixtures with axialstrain increasing are plotted in Figure 15. �e results fromFigure 15 present that the uncon�ned compressive strength ofthese specimens was decreased from 111 to 90 kPa, from 111 to69 kPa, and from 111 to 66 kPa for pure clayey soil andmixtures with CSTC of 10%, 20%, and 30%, respectively. It ispointed out that, when CSTC is 20%, there is an approximately40% decrease in compressive strength of the mixture com-pared with that of pure clayey soil. However, when CSTCexceeds 20%, the e�ect of CSTC on the compressive strength isweak for the mixtures. �e decrease in the compressivestrength of mixtures with CSTC increasing is attributed to thepresence of scrap tire crumbs, which causes the increase of

contact between scrap tire crumbs, resulting in higher resil-ience, higher deformation, and less strength.

4.4.2. E�ects of CSTC on the Failure Modes of Mixtures. �efailure modes of pure clayey soil and the mixture with CSTCof 10% by uncon�ned compression tests are presented inFigures 16(a) and 16(b), respectively. Figure 17 shows thefailure modes of the mixture with CSTC of 20%; this failuremode is similar to that of the mixture with CSTC of 30%. Asshown in Figures 16(a) and 16(b), the inclined plane failureoccurs for pure clay and the mixture with CSTC of 10%.Instead, when the CSTC exceeds 20%, mixture specimens

50 100 150 200 250 300 35030

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90

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240

Clayey soilCSTC = 10%CSTC = 20%CSTC = 30%Fitted curvesfor the mixtures

Resid

ual s

treng

th (k

Pa)

Vertical pressure (kPa)

Residual streng formulaτ = 0.414σ + 18.3τ = 0.394σ + 7.97τ = 0.407σ + 8.65τ = 0.433σ + 10.9

Figure 13: Envelopes of the residual shear strength for mixtures.

2.8

2.4

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0.8

0.4

0.00 50 100 150 200 250 300 350

Clayey soilCSTC = 10%CSTC = 20%CSTC = 30%

Vertical pressure (kPa)

Settl

emen

t (m

m)

Figure 14: Settlement development with vertical pressure formixtures.

0 2 4 6 8 10 12 14 160

20

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120

Axial strain (%)Clayey soilCSTC = 10%CSTC = 20%CSTC = 30%

Axi

al st

ress

(kPa

)

Figure 15: �e axial stress-strain relationships for mixtures.

8 Advances in Materials Science and Engineering

exhibit bulging failure. It is concluded that CSTC may haveinfluence on the failure modes of the mixtures effectively.

5. Conclusions

A series of laboratory tests were performed on scrap tirecrumbs-clayey soil to study the mechanical properties. *efollowing conclusions can be obtained:

(1) Maximum dry unit weight and the correspondingoptimum moisture content of the mixtures decreasewith increasing the CSTC value.

(2) For a given CSTC, the direct shear strength of themixtures increases with the increase in verticalpressure and decreases with the decrease in shearrate. Moreover, the dilation of the mixtures occurs

during shearing, particularly under the condition ofa high CSTC and a low vertical pressure.

(3) Residual shear strength, compressive strength, andconsolidation settlement decrease markedly withCSTC increasing, while start to decrease slightly whenthe CSTC exceeds 20%.

Scrap tire crumbs-clayey soil mixture has the advantagesof higher shear strength, and lower density and settlementcompared with that of pure clayey soil. *is mixture can beused in many geotechnical applications, such as backfillsbehind retaining structures and embankments on softcompressible soil.

Conflicts of Interest

*e authors declare that there are no conflicts of interestregarding the publication of this paper.

Acknowledgments

*is work is jointly supported by the SDUST Research Fund(Grant no. 2015TDJH104).

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mixtures as landfill barrier materials,” Waste Management,vol. 18, no. 1, pp. 9–16, 1998.

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(a) (b)

Figure 16: Inclined plane failure of (a) clayey soil and (b) mixture with CSTC of 10%.

Figure 17: Bulging failure of mixture with CSTC of 20%.

Advances in Materials Science and Engineering 9

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